The present invention relates to a mounting arrangement and in particular a mounting arrangement for a fluid displacement device.
The invention has been developed primarily for mounting an electric motor and blower assembly within the housing of a Continuous Positive Airway Pressure (CPAP) treatment apparatus used in the CPAP treatment of, for example, Obstructive Sleep Apnea (OSA) and other ventilatory assistance treatments such as Non Invasive Positive Pressure Ventilation (NIPPV) and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use and is equally suited in mounting various types of fluid displacement devices including fans, pumps and the like.
CPAP treatment is a common ameliorative treatment for breathing disorders including OSA. CPAP treatment, as described in U.S. Pat. No. 4,944,310, provides pressurised air or other breathable gas to the entrance of a patient""s airways at a pressure elevated above atmospheric pressure, typically in the range 4-20 cm H2O.
It is also known for the level of treatment pressure to vary during a period of treatment in accordance with patient need, that form of CPAP being known as automatically adjust nasal CPAP treatment, as described in U.S. Pat. No. 5,245,995.
NIPPV is another form of treatment for breathing disorders which can involve a relatively higher pressure of gas being provided in the patient mask during the inspiratory phase of respiration and a relatively lower pressure or atmospheric pressure being provided in the patient mask during the expiratory phase of respiration.
In other NIPPV modes the pressure can be made to vary in a complex manner throughout the respiratory cycle. For example, the pressure at the mask during inspiration or expiration can be varied through the period of treatment.
Typically, the ventilatory assistance for CPAP or NIPPV treatment is delivered to the patient by way of a nasal mask. Alternatively, a mouth mask or full face mask or nasal prongs can be used. In this specification any reference to a mask is to be understood as incorporating a reference to a nasal mask, mouth mask, full face mask or nasal prongs.
In this specification any reference to CPAP treatment is to be understood as embracing all of the above described forms of ventilatory treatment or assistance.
A CPAP apparatus broadly comprises a flow generator constituted by a continuous source of air or other breathable gas such as a hospital piped supply or a blower. The gas supply is connected to a conduit or tube, which in turn is connected to a patient mask which incorporates, or has in close proximity, an exhaust to atmosphere for venting exhaled gases. The blower is typically driven by an electric motor controlled by a servo-controller which is in turn under the control of a microcontroller unit.
The blower/motor assembly has hitherto been either directly mounted to the chassis or body of the CPAP apparatus, or isolated therefrom, by foam or other elastomeric sheets or moulded components to dampen vibration and minimise radiated noise. The use of foam sheets is time consuming and expensive as several sections of sheet may have to be installed. The installation of moulded foam components is less time consuming but they are more expensive to produce.
Other rotating or reciprocating machines use inflatable cushions to dampen the machine""s vibration by interposing one or more of the inflatable cushions between the machine and its chassis, housing, ground or other supporting structure. There are two main types of inflatable cushions.
A first type is inflated or filled and thereafter sealed. A disadvantage of this type is they leak and collapse if punctured or otherwise damaged. As a consequence, they are not suitable for use in CPAP apparatus which are sealed during manufacture and not serviceable by customers.
A second type rely on a dedicated constant or intermittent fluid supply to maintain inflation. A disadvantage of this type is the additional complexity and costs associated with the dedicated fluid supply. This second type is also particularly unsuitable for CPAP treatment apparatus which are desirably made as small and light-weight as possible.
It is an object of the present invention to substantially overcome or at least ameliorate one or more of the deficiencies of the prior art.
Accordingly in a first aspect, the present invention provides a mounting arrangement for a fluid displacement device, the mounting arrangement comprising an inflatable cushion device adapted to support the fluid displacement device and in fluid communication with the fluid displacement device, whereby a portion of the fluid displaced by the fluid displacement device inflates and/or maintains inflated the cushion device.
Preferably, the cushion device is in fluid communication with an outlet or interior of the fluid displacement device. The fluid displacement device is preferably a blower, turbine or fan driven by an electric motor.
In an embodiment, the mounting arrangement includes a one way valve interposed between the cushion device and the fluid displacement device, the valve being arranged to only allow fluid transmittal from the fluid displacement device to the cushion device.
In another embodiment, the mounting arrangement includes a pressure regulation valve interposed between the cushion device and the fluid displacement device, or between the cushion device and a zone of lower pressure tan the cushion device (such as atmosphere), the valve being arranged to limit pressurisation of the cushion device to a predetermined maximum.
In a further embodiment, the mounting arrangement includes the one-way valve and the pressure regulating valve.
The arrangement preferably also includes other mounting devices produced from foam or other elastomers. These mounting devices can, for example, act as displacement limiting devices when the cushion is not inflated or provide a resilient base for the cushion.